The present invention relates to technology of electronic devices typified by personal computers provided with a cooling construction by means of a cooling liquid.
The prior art of electronic devices, in which heat generating elements are cooled by a liquid medium (cooling liquid), is disclosed in, for example, JP-A-6-125188 and JP-A-9-268386.
In a liquid cooling system for cooling an electronic device with the use of a cooling liquid, a pump provided in the device circulates a cooling liquid through a metallic pipe and the circulating cooling liquid makes heat exchange with a heat generating element such as CPUs or the like to perform cooling. In such liquid cooling system, the cooling liquid evaporates from a circulating path, which must be sealingly closed, and gas enters the circulating path, whereby the cooling liquid is in some cases decreased to become short.
Therefore, the publications disclose a configuration, in which a cooling liquid tank is arranged in a piping system of a liquid cooling system for cooling a heat generating part of an electronic device. A tank is arranged in the liquid cooling system and a cooling liquid is filled in the tank and a decreased amount of the cooling liquid is supplemented.
In a liquid cooling system, in which a piping system is not filled with a cooling liquid, a phenomenon such as idle running will occur when gas enters a pump in the case where the pump has a low self-priming capability. With such phenomenon, in the prior art, there is a problem that a high cooling effect is not obtained. Also, since air entrained into the pump generates sound, there is caused a need of taking quieting measures.
Further, in the prior art, plastics are used as a material of a tank. With the tank made of such material, permeation or evaporation of cooling liquid from the tank proceeds and air accordingly enters the tank. Thus, the prior art involves problems that air corresponding to the evaporated cooling liquid enters the liquid cooling system and a decrease in the cooling liquid leads to degradation in cooling capability.